Chemical processes



Patented June 25, 1946 CHEMICAL PROCESSES Alfonso M. Alvarado, Wilmington, Wilbur A.

' Lazier, New Castle County, and James H. Werntz, Wilmington, Del., assignors to E. I. du Pont de Nemours & Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application May 6, 1941,

- Serial No. 892,138

.6 Claims. (Cl. 260-513) This invention relates to a process for solubilizing hydrocarbons, and more particularly it relates to a process for solubilizing olefin hydrocarbons. More specifically, this invention relates to an efllcient process for converting olefin hydrocarbons containing at least six and preferably more than eight carbon atoms to soluble aliphatic sulfonic acids having valuable properties as surface-active agents.

With the growing use of synthetic surfaceactive agents in the textile industry, it has become an increasingly important problem not only to develop more eilicient reagents but to find new and cheaper sources of raw materials from which to produce them. Since aliphatic hydrocarbons of the type derived from petroleum are bothcheap and abundant. they have been of particular interest as starting materials for obtaining suitable low cost textile chemicals. It has been proposed, for example, to oxidize certain petroleum fractions with air to produce long-chain acids for use in the manufacture of soap. In general, however, soaps of this type differ but little from soaps prepared by classical methods from fats and are subject to the same disadvan- 25 tages as regards calcium sensitivity. Many of the disadvantages of soaps for use in the fields of textile assistants and finishing agents can be avoided by employing synthetic reagents such as long-chain alkyl sulfates or aliphatic sulfonic acids of appropriate molecular weight. The sulionic acids are particularly valuable, not only because of their high emciency as wetting agents and detergents, but because of their stability toward hydrolysis and efliciency in hard water. Accordingly, the discovery .of a novel and practical synthesis of surface-active sulfonic acids from long-chain oleiin hydrocarbons as provided by the process of this invention comprises animportant contribution to the art of tetxile reagent manufacture.

According to this invention, monoolefin hydrocarbons containing at least six and preferably more than eight carbon atoms are converted to suli'onic acids having valuable properties as surface-active agents by reacting the monoolefln at elevated temperatures with free sulfur to produce a sulfurized olefin, hydrogenating the sulfuriaed olefin at elevated temperatures and pressures in the presence of a sulfactive hydrogenation catalyst to give a product consisting mainly of monothiol, and then oxidizing the hydrogenated sulfurized monooleiln with suitable chemical reagents.

The following general procedure is employed One mole of monoolefln is mixed with at least one, generally with at least two moles and preferably not more than 4 moles of powdered sulfur and heated to a temperature of about C. for

a period of 3 to 8 hours. The resulting mixture,

which consists of a dark-brown somewhat vis cous oil, is transferred without further treatment to a high pressure vessel and hydrogenated at 125 C. to 200 C. and a pressure of about 1500- 2500 lbs. .per square inch during a period of 3 to 8 hours. After cooling the autoclave, the product is removed and distilled to obtain the corresponding monothiol, which is converted to the desired sulfonic acid by oxidation under mild conditions with an appropriate reagent such as 70% nitric acid. The free sulfonic acid is neutralized with an alkali such as sodium hydroxide to obtain a surface-active product characterized by excellent wetting, detergent, and sudsing properties.

The following examples show in greater detail the practice of this invention in several of its modifications. The amounts of materials referred to are in parts by weight, unless otherwise specifled.

Example I Seventy parts of pentadecene-7 and 35 parts of powdered sulfur are charged into a reaction vessel equipped with a thermometer, agitator, a reflux condenser, and a gas inlet tube for blanketing the reaction mixture with an inert gas. The contents of the vesselare heated to about C. After about one hour all the sulfur has dissolved, and the color of the reaction mixture has changed from yellow to brown. Heating at 160 C. is continued for an additional 6.0 to 6.5 hours. to complete the reaction. The product is cooled and diluted with an equal volume of dry ether. (in

standing the ether solution deposits 5 parts of unreacted sulfur, which is separated by filtration. After clarifying the filtrate with activated carbon, evaporation of the ether gives 93 parts of a viscous dark-brown oil containing 31.2% sulfur, as compared to the theoretical value of 31.4% sulfur for 7 Twenty-eight parts of the sulfurized pentadecene is dissolved in 50 parts of dry toluene and charged with 3 parts of cobalt polysulfide catalyst. prepared according to the procedure described in co-pending application of F. K. Signaigo, Serial No. 319,241, filed February 16, 1940, into a steel reaction vessel equipped with an cilicient device for agitation and adapted for operation at high temperatures and pressures. Hy-

in converting long-chain oleflns to sulfonic acids: 65 drogen under pressure is admitted to the reacin the reaction, and the liquidis filtered to separate the catalyst. Fractional distillation of the .catalys't-free oil gives 3.8 parts of unreacted pentadecene-7 suitable for reuse in the first step of the process, 10.2 parts of pentadecanemonothiol, B. P. 173-174 C./16 mm.. 5.4 Parts of pentadecanedithiol, B. P. 196197 C./ 16 mm. and 3.6 parts of high boiling residue. The monothiol fraction is presumably a mixture of pentadecane-7-thiol and pentadecane-8-thiol.

Thirty parts of the pentadecanethiol is added slowly during one hour to 54 parts of 70% nitric acid in a corrosion resistant reaction vessel fitted with a reflux condenser and an efilcient agitating device. Heating at 80 C. is continued for about 4 to 5 hours in order to remove excess nitric acid. The mixture is then diluted with 100 partsof water and exactly neutralized by adding 32 parts of 30% caustic soda solution. Evaporation of the neutral solution gives a thick paste which is extracted with ethanol to separate the pentadecane sodium sulfonate from insoluble inorganic salts. After filterin the latter, the alcohol solution is again evlaporated. On repeating this treatment once or twice, there is obtained 37.5 parts of soft brown solid containing 8.5% of sulfur, as compared to the theoretical value of 10.2% for Dentadecane sodium sulfonate. This product is found to possess powerful sudsing action, good detergentproper ties, and high efficiency as a-wetting agent by the test of Draves and Clarkson (Am. Dyestuffs Reporter, 20, 201 (1931)). 1

Example If Twohundred ten parts of pentadecene-7 is sulfurized by treating with 64 parts of powdered sulfur ata temperature of 150-160 for a period of about 6 hours. The resulting, product is taken up in an equal volume of dry ether, filtered after standing to remove a small amount of unreacted sulfur. and the ether solution evaporated on the steam bath to obtain a viscous darkcharacteristic of tion vessel until the total pressure is between disappears. The resulting homogeneous solution issaturated with sodium chloride and evaporated on the steam bath. The product is extracted with boiling alcohol, filtered to remove inorganic salts, and the solution evaporated.- There is obtained about 38 parts of a brown, brittle solid, which consists of the disodium salt of pentadecane-7,8-disulfonic acid. 0n dissolving the disodium salt in water, persistently foaming solutions are obtained.

Although in the foregoing examples, certain definite conditions of temperature, pressure, re-

. action times, and the like have beenreferred to,

it is to be understood that these values are subject to considerable variation within the scope I of the invention without departing from the spirit reaction vessel, the product is removed, filtered to separate the catalyst, and fractionally distilled to yield 24.5 parts of unreacted pentadecene-l, 52.9 parts of pentadecanemonothiol, 24.3 parts of pentadecane-7, 8-dithiol, and 16.4, parts of residue. The monothiol is oxidized to pentadecane sulfonic acid according to the procedure of- Example I, and the dithiol is treated as follows:

A solution of sodium hypochlorite is prepared by passing 51.4 parts of chlorine into 225 parts of water containing 63 parts of sodium hydroxide and added slowly to a stirred-suspension of 30.6 parts of pentadecane-7,8-dithiolin a solution of 32.5 parts of sodium carbonate and 360 parts of water. The reaction mixture is heated to 75 to 80 C. until substantially all of the'oil layer thereof.

' Broadly speaking, the solubilization of olefin hydrocarbons according to this invention comprises three closely interdependent integrated steps. In the initial step, olefins of suitable structure and molecular weight are converted to the corresponding sulfurized derivatives by direct in teraction with sulfur at temperatures between about C. and about 200 C. and preferably at about C. to 200 C. The reaction can be ture is preferablyhezited for an additional 5 to '1 .hours or more to insure completeness of reaction.

The sulfurized products consist of viscous darkbrown oils containing from one to three atoms of sulfur depending on the actual proportions of I reactants. These materials can be partly purified prior to hydrogenation according to the general method disclosed in Example I or can be employed without further treatment.

In the hydrogenation of sulfurized olefins in accordance with this invention, the crude or partly purified products are treated with hydrogen under a pressure of at least 10 atmospheres and preferably between 100 and 300 atmospheres at a temperature above 100 C. but below 300' C. in the presence of 5 to 15 parts of a sulfactive hydrogenation catalyst. In general, temperatures of 125 C. to 200 C. are sufficient to bring about a smooth and complete hydrogenation during a period of about 2 to 4 hours. Similarly, although the upper pressure limits of the hydrogenation process will be determined only by the practical limitations of the reaction vessel, pressures much above 1000 atmospheres will seldom be necessary. 1

In the practice of this invention, sulfides of the hydrogenating metals of groups 1, VI and VIII of the periodic table are employed as catawlthin this classification are cobalt polysulfide, cobalt monosulfide, nickel sulfide, iron sulfide. molybdenum trisulfide, and copper sulfide. The catalysts are suitably prepared by precipitation from a solution of a soluble salt of the hydrogenating metal with alkali metal or ammonium sulfldes as described in the copending application of F. K. Signaigo, Serial No. 319,241, filed February 16, 1940; alkali metal sulfide activation of an alloy of the hydrogenating metal with aluminum Typical examples of catalysts comin'g' as described in the copending application of B. W. Howk, Serial No. 353,936, filed August 23, 1940; or by treating a pyrophoric hydrogenation catalyst with hydrogen sulfide or sulfur as described in the copending application of F. K. Signaigo, Serial No.- 319,242, filed February 16, 1940. In some cases it may be feasible to carry outthe latter method in 'situ. For batchwise liquid phase hydrogenation, the catalysts of this invention are conveniently employed in finely divided form either asdry powders or suspended in benzene or toluene. For continuous liquid phase hydrogenation, catalyst lumps or briquettes of suitable size are preferred. As mentioned in the above examples, cobalt polysulfide catalyst is particulariy, suited for the hydrogenation of sulfurized olefins to thiols.

On hydrogenation, as described above, sulfurized olefins are converted to a mixture of the corresponding monoand dithiol in the molecular ratio of about two to one. Other products are small amounts of unreacted and regenerated olefin and high boiling residues. These materials can, if desired, be separated by fractional distillation, or the crude product can be employed for oxidation without extensive purification. Generally speaking, it is desirable to top the product in order to remove unreacted olefin for recycle in the process.

Oxidation of the monoand dithiols of this invention to sulionic acids is conveniently carried out ,by treating under mild conditions with suitable reagents such as nitric acid and sodium hypochlorite solutions. In general, nitric acid (70%) is the preferred oxidizing agent for monothiols, whereas hypochlorites are more satisfactory for treating dithiol which may undergo further degradation under more drastic conditions. In either case, the pure thiols or the crude hydrogenation product is treated with the oxidizing reagent at moderate temperatures of the order of 60 ,to 100 C. The length of time and number of treatments required will be governed largely by the ease with which the thiols are converted to soluble sulfonic acids. In some cases, particularly where .the oxidation proceeds vigorously, it may be desirable to dilute the thiols with inert solvents such as carbon tetrachloride, tetrachloroethane and the like. In other instances. oxidizing reagents such as chromic acid, hydrogen peroxide, permanganic acid, or air in the presence of catalysts will be found satisfactory for this transformation. Methods for isolating the products will be found in the examples. A particularly important feature of theinvention is. that th integral steps of the process as described above can be carried out successively in suitable corrosion-resisting high pressure equipment without transfer or loss of material.

In the practice of the invention, there can be employed as raw materials monoolefin hydrocarbons containing at least six and preferably eight or more carbon atoms having at least one hydrogen atom attached to each carbon atom of the ethylenic bond. olefins of this general class can be obtained by dehydration of the corresponding alcohols, decarboxylation of unsaturated acids,

dehydrogenation of saturated hydrocarbons, de-

. carbonylation of unsaturated alcohols, polymerization of lower olefins such as ethylene and propylene, dehydrohalogenation of halogenated paraifin hydrocarbons or from appropriate petroleum cracked distillate fractions. Other sources. of materials will be readily apparent to those skilled in the art. Typical olefins of this group are hexene-3, octene-2, methyl-2-decene- 4, pentadecene-7, hexadecene-l, heptadecene-il, octadecene-2, triacontene-li, pentatriacontene- 17, methyl-i-dodecenel, dimethyl-7,8 pentadecene-7, and hexyl-2-decene-1. These and similar olefins, either alone or in admixture, are smoothly and conveniently converted to surfaceactive sulfonic acids according to this invention.

Aliphatic sulfonic acids coming within the scope of this invention are characterized by a remarkable stability and by outstanding properties as textile reagents or finishing agents. The utility of specific sulfonic acid compositions as wetting agents, detergents, scouring agents, sudslng agents, cotton softeners, and the like will, of course, be governed by considerations of solubility in water, structure and molecular weight. For some uses, it may be desirable to employ the free sulfonic acids, but for the most part, it is preferable to use salts of metals such as sodium, potassium, calcium, and magnesium, or salts of amines such as long-chain primary amines, ethanolamine, glucamine, aniline, Pyridine, piperidine, and the like.

It is apparent that many widely different embodiments of this invention may be made without departing fromthe spirit and scope thereof, and therefore, it is not intended to be limited except as indicated in the appended claims.

We claim:

1. The process which comprises bringing a monoolefin hydrocarbon containing at least 6 carbon atoms into admixture with at least one atom of sulfur per molecule of hydrocarbon, heating the mixture at a temperature between and 200 C. for at least one hour, catalytically hydrogenating the resulting product at a temperature between 100 and 300 C. under a pressure of at least 10 atmospheres until the reaction is complete, cooling the resulting product, and oxidizing to a sulfonic acid.

2. The process which comprises bringing a monoolefin hydrocarbon containing at least 8 carbon atoms into contact with sulfur present in an amount of at least 3 atoms of sulfur per moleing hydrogenated products and bringing same in contact with a 10% nitric acid solution at a temperature between 60 and 100 0., thereby producing sulfonic acids.

3. The process in accordance with claim 1 characterized in that the catalytic hydrogenation reaction is carried out in the presence of a base metal sulfide hydrogenation catalyst.

4. The process in accordance with claim 1 characterized in that the catalytic hydrogenation reaction is carried out in the presence of a terrous group metal sulfide hydrogenation catalyst.

5. The process in accordance with claim 1 characterized in that the catalytic hydrogenation reaction is carried out in the presence of a cobalt polysulfidc hydrogenation catalyst.

6. The process in accordance with claim 1 characterized in that the catalytic hydrogenation reaction is carried out in the presence of a molybdenum sulfide hydrogenation catalyst.

ALFONSO M, ALVARADO. WILBUR A. LAZIER. JAMES H. WERNTZ. 

